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Minimum psu for 3 GTX280s? - Page 2

post #11 of 18
Antec 1000w much cheaper then corsair and is rock solid.
post #12 of 18
Whatever you choose, don't go for the minimum... definitely get more. I'd say that you should solely be looking at 1200W PSU's. As I'm sure you know, just because its 1200W doesn't mean you are always using that much... but if you need to, its there. But to help myself and others give good recommendations, what price range are you trying to stick to? If price isn't a concern, then definitely get the PCP&C Turbo-Cool 1200W ESA (best current price). Its got 100A on a single 12v rail, and is designed for enthusiast users, like us overclockers... but as you can see it isn't exactly "cheap". If price is an issue, what's your limit?
    
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post #13 of 18
Quote:
Originally Posted by oneluvballer21 View Post
Whatever you choose, don't go for the minimum... definitely get more. I'd say that you should solely be looking at 1200W PSU's. As I'm sure you know, just because its 1200W doesn't mean you are always using that much... but if you need to, its there. But to help myself and others give good recommendations, what price range are you trying to stick to? If price isn't a concern, then definitely get the PCP&C Turbo-Cool 1200W ESA (best current price). Its got 100A on a single 12v rail, and is designed for enthusiast users, like us overclockers... but as you can see it isn't exactly "cheap". If price is an issue, what's your limit?
he could run 3 seperate power supplies with one going to each card for less than half of that beast lol. Get a case that supports dual power supplies, it will save you a lot of money.
post #14 of 18
Quote:
Originally Posted by skydeaner View Post
he could run 3 seperate power supplies with one going to each card for less than half of that beast lol. Get a case that supports dual power supplies, it will save you a lot of money.
To be honest, if I was investing in three GTX280's, and I wanted a PSU to safely run them, and OC my whole system as well, I wouldn't trust anyone but PCP&C... and I would gladly pay that price tag if I was building his system for myself, assuming I could afford it. If he wants to drop $1100+ on video cards, he should be willing to make the sacrifice to get the best PSU for his system, and PCP&C is always the best... sometimes others are on par, but not usually. I mean why spend $200 on a PSU that you're going to stress the hell out of, and risk it frying your very expensive components?? Consistently, PCP&C uses the best internal components out there, which is why they are the most stable PSU's on the market. I mean he doesn't have to get the ESA model, that was just if money is no concern. Newegg has the non-ESA model for $449 if that's any better...

This system is a high cost investment as is, and the PSU is one of the most overlooked components when it comes to overclocking a system, as it can hinder all the components you wish to OC if you don't pick your PSU wisely... unstable voltage rails at high current usage is usually the biggest problem for OCing, as in optimal conditions you want a 12v rail that supplies 12.00v, or say 12.10v, at both idle and peak usage... same voltage for any amount of usage. Granted that's not always 100% possible, but PCP&C is almost always damn close to perfect in that area. Sorry, but for a performance system for myself, I'll only buy PCP&C.

EDIT: I have three systems, and use two Turbo-Cool 850 SSI PSU's in two of them, and the third (a low wattage server) uses a Turbo-Cool 510... its PCP&C or nothing.
Edited by oneluvballer21 - 12/17/08 at 6:10pm
    
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post #15 of 18
Quote:
Originally Posted by caraboose View Post
What would the minimum psu be for 3 GTX280s and a Q9550?
I would hands down get the Corsair 1000w. It's lots of good, clean power, and it has all the right cable connections so you don't need adapters.
post #16 of 18
Quote:
Originally Posted by oneluvballer21 View Post
unstable voltage rails at high current usage is usually the biggest problem for OCing, as in optimal conditions you want a 12v rail that supplies 12.00v, or say 12.10v, at both idle and peak usage... same voltage for any amount of usage. Granted that's not always 100% possible, but PCP&C is almost always damn close to perfect in that area. Sorry, but for a performance system for myself, I'll only buy PCP&C.
Actually there are plenty of units that have better regulation than the Turbo-cools. The Turbo-cools have good but not great regulation (definitely not perfect), efficiency is a little behind the times and ripple suppression and build quality are top notch. As for unstable voltages affecting OCing, I would like to see some proof. If you mean unstable as in out of spec of 5% (11.4-12.6V is the range of safe voltages) then sure, but as long as voltages are within spec they will have zero affect on OCing. CPUs and GPUs both regulate 12V down to whatever they need to run so the exact value of the 12V does not matter as long as it is within spec. Sure the Turbo-cools are good but they are definitely not worth their price since there are better or similar performing units for much, much less.
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post #17 of 18
Quote:
Originally Posted by shinji2k View Post
Actually there are plenty of units that have better regulation than the Turbo-cools. The Turbo-cools have good but not great regulation (definitely not perfect), efficiency is a little behind the times and ripple suppression and build quality are top notch. As for unstable voltages affecting OCing, I would like to see some proof. If you mean unstable as in out of spec of 5% (11.4-12.6V is the range of safe voltages) then sure, but as long as voltages are within spec they will have zero affect on OCing. CPUs and GPUs both regulate 12V down to whatever they need to run so the exact value of the 12V does not matter as long as it is within spec. Sure the Turbo-cools are good but they are definitely not worth their price since there are better or similar performing units for much, much less.
I bought each of my 850 SSI's for $100 including shipping, and the 510 for $40... all under warranty with years (plural) left to go... of course, on eBay. You don't always have to pay retail prices for high quality. That's where research can pay off huge if you know what to look for.

From the tests I've recently seen, the 1000HX shows about a 32mV ripple on the +12v rail from idle to load (which was better than the other two PSU's in the review), but the PCP&C 1200w showed 12mV ripple in a different Anandtech review.

As for voltage rail stability and having a +12v rail go from say 12.10v to 11.95v, it won't affect most overclocking, but it can affect your ability to squeeze the last bit of potential out of your components. I haven't read anything for or against it, so its still just theory. I mean its hard to test that, as once you go too far in an OC and have issues, most people simply assume its the CPU or GPU that has the limitation. While there is some truth to it, I also believe that squeezing that last 1-2% can be the difference in the PSU's ability to deliver a +12v current that is consistent from idle to load. I suppose it is theoretically possible to test this with two PSU's that are identical in as many ways as possible, save the voltage rail consistency and stability, and see which allows for a high 100% stable system OC... but that would still be very hard to do. Anyway, this is something that makes sense to me, so I subscribe to it 100%. And I'm not the only person who believes this either... its not my 'original' idea.
    
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post #18 of 18
Quote:
Originally Posted by oneluvballer21 View Post
From the tests I've recently seen, the 1000HX shows about a 32mV ripple on the +12v rail from idle to load (which was better than the other two PSU's in the review), but the PCP&C 1200w showed 12mV ripple in a different Anandtech review.
Anandtech, lol. Chris's ripple testing is inconsistent at best. I think you may be using the terminology wrong anyway. Voltage regulation is the measure of change between idle and load voltages (min and max load basically). A good number to hit for a 1kW PSU will be a change of 2%, with a change of 1% being great. So on a PSU that can supply 80A (960W) on the 12V going from a minimum load of ~2A to a load of 80A, a drop of 0.24V is what I consider good and 0.12V to be great. Ripple is a measure of AC waveform that is still present in the DC outputs.

So let's compare the Corsair and Turbo-cool.

Let's look at the 12V regulation:
Corsair - going from 14A to 68A we see a drop of 0.22V
Turbo-cool- going from 14A to 72A we see a drop of 0.25V

Not much difference there.

Efficiency:
Corsair at 25% load - 82% efficient, peak efficiency is 86%
Turbo cool- @25% load 75% efficient, peak is 79%

Ripple Suppression
Corsair- 12V peak ripple is ~70mV
Turbo-cool- 12V peak ripple is ~20mV

Clearly the Turbo-cool is better here, but ATX spec allows up to 120mV p-p so the Corsair is still well within limits. Usually I would say the Corsair is the clear winner since it is cheaper, has a much quieter fan and is modular, but surprisingly the Turbo-cool is priced well ATM.
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